WO2011111409A1

WO2011111409A1 - Method for manufacturing optical element

Info

Publication number: WO2011111409A1
Application number: PCT/JP2011/050254
Authority: WO
Inventors: 博之新藤; 武嗣白石
Original assignee: コニカミノルタオプト株式会社
Priority date: 2010-03-09
Filing date: 2011-01-11
Publication date: 2011-09-15

Abstract

A diffraction grating (7) is formed on the surface (6) of a base material (1) by a nano-imprinting method. The base material (1) is cut on a cutting surface (A) that intersects the surface (6) in the longitudinal direction of the base material (1). The base material (1) is cut on a cutting surface (B) in the longitudinal direction at a predetermined distance from the cutting surface (A). Thus, a cut piece (30) sandwiched between the cutting surface (A) and the cutting surface (B) is obtained from the base material (1). A plurality of optical elements are manufactured by cutting, at predetermined intervals, the cut piece (30) on the cutting surfaces that intersect the cutting surface (A) and the cutting surface (B).

Description

Optical element manufacturing method

The present invention relates to a method for manufacturing an optical element.

A method for producing a minute optical element has been proposed. For example, Patent Document 1 describes a method of manufacturing a minute prism having a side length of less than 1 mm. In the manufacturing method described in Patent Document 1, a plurality of minute prisms (microprisms) are manufactured by cutting a large prism having an inclined surface at a plurality of locations.

Also, there is a demand for a composite microprism in which a fine structure is provided on the optical surface of the prism. A diffraction grating or a lens corresponds to the fine structure.

For example, in a hard disk device, an optically assisted magnetic recording method has been developed to further increase the recording density. The size of the magnetic head of the optically assisted magnetic recording system is, for example, a length of 0.85 mm, a width of 0.7 mm, and a thickness of 0.23 mm. Since the magnetic head itself is thus small, the optical element used in the magnetic head is also required to have a size of less than 1 mm. As a composite microprism for light assist, for example, there is a microprism provided with a diffraction grating having a fine pitch of submicron order.

JP 2009-276366 A

For example, by forming a diffraction grating on the optical surface of a glass microprism manufactured by the method described in Patent Document 1 by a nanoimprint method, a microprism having a fine pitch diffraction grating is obtained. However, since the microprism itself is very small, it is very difficult to handle. Therefore, when a diffraction grating is formed on the microprism, it is very difficult to perform positioning and angle adjustment between the mold for transferring the diffraction grating and the microprism. As a result, it becomes difficult to accurately transfer the shape of the diffraction grating to the microprism. When transferring a fine structure other than the diffraction grating, there is a similar difficulty.

The present invention solves the above-described problems, and an object thereof is to provide a method of manufacturing an optical element that is easy to handle and can form a fine structure with high accuracy.

The present invention includes a first step of forming a microstructure on a surface of a rod-shaped base material, and a first step of cutting the base material at a first cut surface that intersects the surface and extends along the longitudinal direction of the base material. Cutting the base material at a second cutting surface that intersects the surface and extends along the longitudinal direction at a predetermined distance from the first cutting surface, and the first cutting surface and the first cutting surface. A second cutting step for obtaining a cut piece sandwiched between two cut surfaces from the base material, and a third cut surface intersecting the first cut surface and the second cut surface, And a third cutting step of producing a plurality of optical elements by cutting the pieces at predetermined intervals.

In the method of manufacturing an optical element, the base is a triangular prism having a triangular bottom surface, and in the first step, the microstructure is formed with the first side surface of the triangular prism as the surface, and the first In the cutting step, the base material is cut at the first cutting surface that intersects the second side surface and the first side surface of the triangular prism and extends along the longitudinal direction, and in the second cutting step, The substrate may be cut at the second cut surface that intersects the second side surface and the first side surface along the longitudinal direction at the predetermined distance from the first cut surface. Good.

The angle formed between the first side surface and the second side surface is 90 ° −θ (0 ° <θ <90 °), and in the first cutting step, the angle is perpendicular to the second side surface. Preferably, the base material is cut at the first cut surface, and in the second cutting step, the base material is cut at the second cut surface perpendicular to the second side surface.

In the method of manufacturing an optical element, the base material is a triangular prism having an isosceles triangular bottom surface, and in the first step, the fine structure is formed with the first side surface including the bottom of the triangular prism as the surface. Forming, in the first cutting step, the first cutting along the longitudinal direction intersecting the second side surface and the first side surface each including one side of two equal sides of the isosceles triangle The base material is cut at a surface, and in the second cutting step, the second side surface and the first side surface intersect each other at the predetermined distance from the first cut surface, and the longitudinal direction. The first cut piece sandwiched between the first cut surface and the second cut surface is obtained from the base material by cutting the base material at the second cut surface along the line, In the third cutting step, the first cut piece is cut off at the third cut surface. The plurality of optical elements are manufactured by cutting at regular intervals, intersecting the third side surface including the other two sides of the equal isosceles triangle and the first side surface, respectively, along the longitudinal direction A fourth cutting step of cutting the base material at a fourth cut surface; and the third side surface and the first side surface intersecting each other at the predetermined distance from the fourth cut surface, A fifth cut piece sandwiched between the fourth cut surface and the fifth cut surface is obtained from the base material by cutting the base material at a fifth cut surface along the longitudinal direction. Cutting the second cut piece at the predetermined interval at the cutting step and a sixth cut surface intersecting the fourth cut surface and the fifth cut surface. And a sixth cutting step to be produced.

The base angle of the isosceles triangle is 90 ° −θ (0 ° <θ <90 °), and in the first cutting step, the first cut surface is perpendicular to the second side surface. The base material is cut, and in the second cutting step, the base material is cut at the second cutting surface perpendicular to the second side surface, and in the fourth cutting step, the third side surface is cut. It is preferable that the base material is cut at the fourth cut surface perpendicular to the substrate, and the base material is cut at the fifth cut surface perpendicular to the third side surface in the fifth cutting step.

In the first step, the fine structure including a first fine structure and a second fine structure having mutually inverted shapes is formed on the first side surface, and the first cutting step and the first fine structure are formed. In the second cutting step, the first cut surface and the second cut surface intersecting the second side surface and the first microstructure respectively cut the base material to cut the base material. In the fourth cutting step and the fifth cutting step, the fourth cut surface and the second cut surface intersecting the third side surface and the second fine structure, respectively, are obtained. It is preferable to obtain the second cut piece by cutting the base material with the cut surface of 5.

In the optical element manufacturing method, an optical film may be formed on the surface on which the fine structure is formed between the first step and the first cutting step.

The optical film is preferably a reflective film.

In the above optical element manufacturing method, a tip including the surface on which the fine structure is formed and the surface formed by the second cut surface may be chamfered.

In the optical element manufacturing method, the first cut surface and the second cut surface may not be parallel.

In the optical element manufacturing method, in the first step, a flowable material is provided between the mold having the microstructure and the base material, and the mold and the base material By sandwiching the flowable material, the shape of the fine structure is transferred to the flowable material, and the flowable material to which the shape of the fine structure has been transferred is cured, so that the surface of the substrate has the fine structure. A structure may be formed.

The fluid material is a resin as an example.

In the optical element manufacturing method, in the first step, the fine structure is formed in a partial region of the surface, and in the first cutting step and the second cutting step, the fine structure is formed. The substrate may be cut across the position where is formed.

In the first step, it is preferable that the fine structure is formed in a region wider than the effective optical surface of the optical element in a partial region of the surface.

In the optical element manufacturing method, the fine structure is a diffraction grating as an example.

According to the present invention, an optical element is produced by forming a fine structure on a rod-shaped base material and cutting the base material on which the fine structure is formed. Since such a base material is used, handling becomes easy. That is, since the fine structure is formed on the rod-shaped substrate without forming the fine structure on the minute optical element, the handling becomes easy. For example, when forming a fine structure, it is possible to perform alignment and angle alignment of the base material with high accuracy. This makes it possible to form a fine structure on the substrate with high accuracy.

It is a perspective view of the base material concerning a 1st embodiment of this invention. It is a perspective view of the metal mold | die which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the optical element which concerns on 1st Embodiment of this invention, and is a front view of a base material and a metal mold | die. In 1st Embodiment, it is a perspective view of the base material in which the diffraction grating was formed. In 1st Embodiment, it is a front view which shows the state which mounted the base material on the process stand. It is a perspective view of the cutting piece which concerns on 1st Embodiment of this invention. It is a perspective view of the optical element produced by the manufacturing method of the optical element which concerns on 1st Embodiment. It is a front view of the metal mold | die which concerns on the modification 1. FIG. It is a perspective view of the base material which concerns on 2nd Embodiment of this invention. It is a front view of the metal mold | die which concerns on 2nd Embodiment of this invention. In 2nd Embodiment, it is a front view of the base material in which the diffraction grating was formed. In 2nd Embodiment, it is a front view which shows the state which mounted the base material on the process stand. In 2nd Embodiment, it is a front view which shows the state which mounted the base material on the process stand. It is a front view of the metal mold | die which concerns on the modification 2. FIG. It is a perspective view of the base material which concerns on 3rd Embodiment of this invention. It is a front view of the metal mold | die which concerns on 3rd Embodiment of this invention. In 3rd Embodiment, it is a front view which shows the state which mounted the base material on the process stand. It is a front view of the cutting piece which concerns on 3rd Embodiment. It is a front view of the cutting piece which concerns on 3rd Embodiment. It is a perspective view of the base material which concerns on 4th Embodiment of this invention. It is a front view of the metal mold | die which concerns on 4th Embodiment of this invention. It is a front view of the base material concerning a 4th embodiment of this invention. In 4th Embodiment, it is a front view which shows the state which mounted the base material on the process stand. In 4th Embodiment, it is a front view which shows the state which mounted the base material on the process stand.

[First Embodiment]
(Substrate 1)
A method for manufacturing an optical element according to the first embodiment of the present invention will be described. With reference to FIG. 1, the base material which concerns on 1st Embodiment is demonstrated. FIG. 1 is a perspective view of a base material. As an example, the base material 1 is a rod-shaped prism having a triangular cross section. Specifically, the substrate 1 is a prism (triangular prism) having a triangular bottom surface 2 and a bottom surface 3. The side surface of the substrate 1 includes a surface 4, a surface 5, and a surface 6. As an example, the surface 4 and the surface 5 are orthogonal to each other, and the surface 6 is inclined with respect to the surface 4 and the surface 5. For example, the angle formed by the surface 5 and the surface 6 is an angle (90 ° −θ) (0 ° <θ <90 °). The length of each side of the bottom surface 2 and the bottom surface 3 is preferably about 3 mm to 5 mm. The substrate 1 is a rod-shaped prism (triangular prism) having a long distance between the bottom surface 2 and the bottom surface 3 (distance in the longitudinal direction (X direction in the drawing)). The distance between the bottom surface 2 and the bottom surface 3 (the distance in the longitudinal direction) is preferably about 10 mm to 50 mm. In other words, the sides of the

surfaces

4, 5, and 6 that are not included in the bottom surface 2 and the bottom surface 3 are preferably about 10 mm to 50 mm in length. The material of the substrate 1 is, for example, glass.

In the first embodiment, a plurality of optical elements are produced by cutting the substrate 1. The optical element corresponds to, for example, a prism formed with a diffraction grating as an example of a fine structure, a diffraction element, or a lens. As an example, a case where a prism having a diffraction grating is manufactured will be described. The base material 1 is cut out from the square bar. For the convenience of processing, the surface accuracy of the surface 6 is higher than that of the surface 4 and the surface 5. Therefore, it is preferable to form a diffraction grating on the surface 6. For example, the surface 6 is preferably subjected to surface finishing with high surface accuracy in advance, and a diffraction grating is formed on the surface 6.
(Mold 10 for transferring diffraction grating)
With reference to FIG. 2, the metal mold | die which concerns on 1st Embodiment is demonstrated. FIG. 2 is a perspective view of the mold. On one surface 11 of the mold 10, a transfer structure 12 for transferring a blazed diffraction grating is formed. The transfer structure 12 has a plurality of grooves along one direction. The cross-sectional shape of the groove is serrated. In FIG. 2, the pitch of the transfer structure 12 is illustrated in an enlarged manner for the purpose of explanation, but the actual pitch of the transfer structure 12 is a fine pitch on the order of submicrons. As an example, the pitch of the transfer structure 12 is less than 1 μm. The transfer structure 12 may be formed on the entire surface 11, or may be formed on a part of the surface 11.

The mold 10 is manufactured by processing a metal such as nickel (Ni). The mold 10 may be a glass transparent substrate. For example, the mold 10 is manufactured by forming the transfer structure 12 on the surface of the glass substrate by anisotropic etching. Alternatively, a transparent resin is applied to a metal mold having the same shape as the diffraction grating formed on the substrate 1, and the shape of the diffraction grating is transferred to the transparent resin by photocuring or heat curing. A transparent resin to which the shape is transferred may be used as the mold 10. Or you may produce the metal mold | die 10 by injection molding.
(Optical element manufacturing method)
With reference to FIG. 3 to FIG. 6, a method for manufacturing an optical element according to the first embodiment will be described.
(1. Formation of diffraction grating)
First, a diffraction grating is formed on the surface 6 of the substrate 1 by a nanoimprint method. A method of forming a diffraction grating will be described with reference to FIG. FIG. 3 is a front view of the base material and the mold. Here, (1. Formation of diffraction grating) functions as the first step in the present invention, the surface 6 functions as the surface and the first side surface in the present invention, and the surface 5 corresponds to the second step in the present invention. Acts as a side of
(1-A. Application of resin 13)
As shown in FIG. 3A, a photocurable resin 13 that is an example of a fluid material is applied to the surface 11 of the mold 10 on which the transfer structure 12 is formed, and shown in FIG. As described above, a resin 13 is provided on the transfer structure 12. For example, PAK-02 (Toyo Gosei Co., Ltd., nd = 1.51) is used as the photo-curable resin. In this embodiment, the material of the photocurable resin is not limited.
(1-B. Transfer of transfer structure 12)
Next, as shown in FIG. 3C, the base material 1 that is a prism is pressed against the mold 10. Specifically, the surface 6 (transfer surface) of the substrate 1 is pressed against the transfer structure 12 coated with the resin 13. In this way, the transfer structure 12 of the mold 10 is transferred to the resin 13 by sandwiching the resin 13 between the substrate 1 and the mold 10.

For example, for the base material 1, attention is paid to the ridge line formed by the surface 5 and the surface 6. For the mold 10, attention is paid to the boundary line between the transfer structure 12 and the flat portion of the surface 11. The rotation of the substrate 1 is adjusted around the normal of the surface 6 while observing with an observation camera (not shown) so that the ridge line related to the substrate 1 and the boundary line related to the mold 10 are parallel. Since the base material 1 has an elongated rod-like shape, it can be observed over a wide range, and a slight rotational deviation can be detected. Therefore, the ridgeline related to the substrate 1 and the boundary line related to the mold 10 can be matched in parallel. That is, the ridgeline related to the substrate 1 and the direction of the groove of the transfer structure 12 can be matched in parallel.

Alternatively, two pins may be provided at a predetermined distance in the vicinity of the transfer structure 12 in the mold 10. While pressing the ridge line of the substrate 1 against the pin, the surface 6 of the substrate 1 is pressed against the transfer structure 12 coated with the resin 13. In this way, positioning and parallel determination may be performed by pins.

Alternatively, the transfer structure 12 may be transferred to the resin 13 by applying the resin 13 to the surface 6 of the substrate 1 and pressing the transfer structure 12 of the mold 10 against the resin 13.
(1-C. Curing treatment)
As shown in FIG. 3C, the resin 13 is cured by irradiating the substrate 14 with ultraviolet rays 14 from the substrate 1 side in a state where the substrate 1 is pressed against the mold 10. When the mold 10 is made of a transparent substrate, ultraviolet rays may be irradiated from the back surface of the mold 10. The back surface is a surface facing the surface 11 on which the transfer structure 12 is formed. Since the mold 10 is a transparent substrate, the ultraviolet light incident from the back surface passes through the mold 10 and is irradiated to the resin 13.

After the resin 13 is cured, the substrate 1 is separated from the mold 10. Through the above steps, a diffraction grating is formed on the surface 6 of the substrate 1.

In the formation of the diffraction grating according to the first embodiment, a photocurable resin is used as the fluid material, but a thermosetting resin may be used. When a thermosetting resin is used, the resin is cured by heating instead of ultraviolet irradiation.

A sol-gel glass may be used as the fluid material. In this case, the gel-like sol-gel glass is cured by applying a gel-like sol-gel glass to the mold 10 and heating the base material 1 for a predetermined time while being pressed against the mold 10. Thereafter, the base material 1 is released from the mold 10, and the base material 1 on which the diffraction grating is formed is subjected to heat treatment to polymerize and completely solidify the sol-gel glass. Further, SOG (spin on glass) may be used as the fluid material.
(Substrate 1 on which diffraction grating is formed)
FIG. 4 shows the substrate 1 on which a diffraction grating is formed. FIG. 4 is a perspective view of the substrate. A fine pitch diffraction grating 7 is formed on the surface 6 of the substrate 1. In FIG. 4, the pitch of the diffraction grating 7 is illustrated in an enlarged manner for the sake of explanation, but the actual pitch of the diffraction grating 7 is a fine pitch on the order of submicrons. As an example, the pitch of the diffraction grating 7 is less than 1 μm. The diffraction grating 7 may be formed in a partial region of the surface 6 or may be formed on the entire surface 6.

A reflective film such as gold (Au) is formed as an example of an optical film on the surface 6 on which the diffraction grating 7 is formed. As a film forming method, for example, a vapor deposition method or a sputtering method may be used.
(2. Cutting process)
Next, the base material 1 on which the diffraction grating 7 is formed is cut to produce a plurality of optical elements. With reference to FIG.5 and FIG.6, a cutting process is demonstrated. FIG. 5 is a front view showing a state in which the base material is placed on the processing table. FIG. 6 is a perspective view of a cut piece.
(2-A. Fixed)
As shown in FIG. 5, the upper surface 21 of the processing table 20 is a surface that fixes the cutting reference surface of the substrate 1. The base material 1 is fixed to the processing table 20 with the cutting reference plane of the base material 1 facing the upper surface 21 of the processing table 20. For example, the substrate 5 is fixed to the processing table 20 with the surface 5 of the substrate 1 as a cutting reference surface and the surface 5 facing the upper surface 21 of the processing table 20. For example, a dicing sheet (dicing tape) 22 is provided on the upper surface 21 of the processing table 20, and the substrate 1 is provided on the dicing sheet 22 by bringing the dicing sheet 22 and the surface 5 into contact with each other.

Alternatively, the base material 1 may be fixed to the processing table 20 by a fixing means (not shown) such as a clamp without providing the dicing sheet 22. In this case, the surface 5 (cutting reference surface) of the substrate 1 is brought into contact with the upper surface 21 of the processing table 20, and the surface 5 is pressed against the upper surface 21, and the substrate 1 is fixed to the processing table 20 by fixing means such as a clamp. Secure to.
(2-B. Cutting)
After fixing the base material 1 to the processing table 20, the base material 1 is cut at a position where the diffraction grating 7 is formed. Specifically, the base material 1 is cut along the cut surface A (first cut surface) intersecting with the diffraction grating 7 (first cutting step). The cutting plane A is a plane parallel to the longitudinal direction (X direction) of the substrate 1 and perpendicular to the cutting reference plane (plane 5). In other words, the cutting plane A is a plane that is parallel to the ridgeline formed by the

planes

4 and 5 and is perpendicular to the cutting reference plane (plane 5). For example, the substrate 1 is cut along the cut surface A using a dicing blade 23. Next, the base material 1 is cut along a cutting plane B (second cutting plane) parallel to the cutting plane A and spaced a predetermined distance inside the cutting plane A (second cutting step). The cut surface B intersects the diffraction grating 7. Note that the second cutting step may be performed first, and then the first cutting step may be performed.

The cut surface A and the cut surface B may not be perpendicular to the cutting reference surface (surface 5). For example, by tilting the work table 20 or the dicing blade 23 with respect to the cutting reference plane (surface 5), the substrate 1 can be cut at an angle shifted from a direction perpendicular to the cutting reference plane (plane 5). Alternatively, the substrate 1 may be cut at an angle shifted from a direction perpendicular to the cutting reference plane (surface 5) by providing the dicing blade 23 with a taper. Moreover, the cut surface A and the cut surface B do not need to be parallel.

In addition, you may cut | disconnect to the middle of the process base 20, and you may cut | disconnect to the middle of the dicing sheet | seat 22 without making a notch | incision to the process base 20. FIG. When the thickness of the dicing sheet 22 is sufficient, the dicing sheet 22 may be used as a processing table without using the processing table 20. As described above, the processing table used for cutting may or may not include the processing table 20, or may or may not include the dicing sheet 22. That is, as the processing table, the processing table 20 may be used, the dicing sheet 22 may be used, or a configuration including the processing table 20 and the dicing sheet 22 may be used.

The rod-shaped cut piece 30 is obtained by the above cutting. FIG. 6 shows a cut piece 30. The cut piece 30 is a prism having a substantially trapezoidal surface 31 and a surface 32 as bottom surfaces. The surface 31 corresponds to the bottom surface 2 of the substrate 1. The surface 32 corresponds to the bottom surface 3 of the substrate 1. The side surface of the cut piece 30 includes a surface 33, a surface 34, a surface 35, and a surface 36. The surface 33 corresponds to the cut surface A and includes the upper base of the trapezoid (the surface 31 and the surface 32). The surface 34 corresponds to the cut surface B and includes the lower base of the trapezoid (the surface 31 and the surface 32). The surface 35 corresponds to the surface 6 of the substrate 1 and is inclined with respect to the surface 33 and the surface 34. The angle formed by the surface 34 and the surface 35 is an angle θ (0 ° <θ <90 °, for example, θ = 45 °). A diffraction grating 7 is formed on the surface 35 (surface 6). The surface 36 corresponds to the surface 5 of the substrate 1 and is orthogonal to the surface 33 and the surface 34.

The surface 33 and the surface 34 may be parallel or may not be parallel. That is, by cutting the substrate 1 with the cut surface A and the cut surface B being parallel, the cut piece 30 in which the surface 33 and the surface 34 are parallel is obtained. By cutting the substrate 1 with the cut surface A and the cut surface B being non-parallel, a cut piece 30 in which the surface 33 and the surface 34 are non-parallel is obtained.

Then, the cut pieces 30 are cut at a plurality of locations at predetermined intervals along the cut surface C (third cut surface) (third cutting step). The cut surface C is a surface parallel to the surface 31 and perpendicular to the surface 34. A plurality of optical elements are obtained by cutting the cutting piece 30 at a plurality of locations. Note that the cut surface C may not be parallel to the surface 31.
(Optical element)
FIG. 7 shows an optical element. FIG. 7 is a perspective view of the optical element. The optical element 30A is a prism having a substantially trapezoidal surface 37 and a surface 38 as bottom surfaces. The surface 37 and the surface 38 correspond to the cut surface C. The side surface of the optical element 30 A includes a surface 33, a surface 34, a surface 35, and a surface 36. The surface 33 corresponds to the cut surface A and includes the upper base of the trapezoid (the surface 37 and the surface 38). The surface 34 corresponds to the cut surface B and includes the lower base of the trapezoid (the surface 37 and the surface 38). The surface 35 corresponds to the surface 6 of the substrate 1 and is inclined with respect to the surface 33 and the surface 34. The angle formed by the surface 34 and the surface 35 is an angle θ (0 ° <θ <90 °). A diffraction grating 7 is formed on the surface 35 (surface 6). A reflective film is formed on the surface 35 (surface 6). The surface 36 corresponds to the surface 5 of the substrate 1 and is orthogonal to the surface 33 and the surface 34. As an example, the length of each side of the optical element 30A is around 0.5 mm.

For example, when the optical element 30A is used for an optically assisted magnetic head, the optical element 30A is mounted on the magnetic head with the surface 33 facing the disk. It is preferable that the angle formed by the surface 33 and the surface 36 is smaller than 90 ° so that the surface 33 does not protrude to the disk side than the slider. That is, it is preferable to cut the base material 1 by inclining the cutting plane A with respect to the cutting reference plane (plane 5). For example, the surface 33 and the surface 34 are formed non-parallel so that the angle formed by the surface 33 and the surface 36 is less than 90 °.

The optical element 30A can be used as a surface reflection type microprism with a diffraction grating. For example, the surface 35 (surface 6) on which the diffraction grating 7 is formed is irradiated with light from the outside of the optical element 30A and reflected by the surface 35. The light reflected by the surface 35 is irradiated onto the disk via an optical waveguide formed inside the slider of the hard disk device, for example.

As described above, according to the manufacturing method according to the first embodiment, the fine transfer structure 12 is transferred to the large rod-shaped base material 1 by the nanoimprint method, and the base material 1 to which the transfer structure 12 is transferred is cut. Element 30A is fabricated. Since such a large substrate 1 is used, handling becomes easy, and alignment and angle alignment can be performed with high precision between the substrate 1 and the mold 10. Therefore, it becomes possible to transfer the transfer structure 12 to the substrate 1 with high accuracy. As a result, an optical element 30A to which the transfer structure 12 is transferred with high accuracy is obtained.

In addition, after transferring the fine transfer structure 12 to the base material 1 and before cutting, by forming a reflective film on the surface 6 to which the transfer structure 12 is transferred (surface 6 on which the diffraction grating 7 is formed), It is possible to reduce the number of manufacturing steps. Conventionally, a reflective film is formed on an individual composite microprism (optical element). In this case, it is necessary to arrange the individual optical elements one by one on a film forming jig. Therefore, many man-hours were required. On the other hand, according to the method according to the first embodiment, since the reflective film is formed on the large rod-like base material 1, it is possible to significantly reduce the number of man-hours for the arrangement.

In addition, when a microprism having a fine pitch diffraction grating is manufactured by resin injection molding or glass mold, transfer to the inverted shape of the diffraction grating formed on the mold becomes insufficient, and desired optical characteristics are obtained. It is difficult to secure. On the other hand, in the first embodiment, the diffraction grating is formed by the nanoimprint method. Since the viscosity of the resin before curing is relatively low, even a fine structure can be accurately transferred, and as a result, high optical characteristics can be obtained. According to the first embodiment, since the edge portion of the diffraction grating shape can be transferred, high diffraction efficiency can be obtained.
(Modification 1)
In the first embodiment described above, the diffraction grating 7 is formed on the entire surface 6 of the substrate 1 and is formed on the entire surface 35 of the optical element 30A. As a first modification, the diffraction grating 7 may be formed only in a range including the effective optical surface of the surface 35 of the optical element 30A. FIG. 8 shows a mold according to the first modification. FIG. 8 is a front view of the mold. On one surface 11 of the mold 10A, a transfer structure 12 is formed in a partial region. The range in which the transfer structure 12 is formed is wider than the effective optical surface of the surface 35 of the optical element 30 A and narrower than the surface 6 of the substrate 1. A diffraction grating 7 is formed on the surface 6 of the substrate 1 using this mold 10A. Thereby, the diffraction grating 7 is formed in a partial region of the surface 6 of the substrate 1. By cutting the substrate 1 on which the diffraction grating 7 is formed in a part of the region, an optical element 30A in which the diffraction grating 7 is formed on the effective optical surface of the surface 35 is obtained. Thus, since the transfer structure 12 is formed in a partial region of the mold 10A, the region where the transfer structure 12 is to be processed becomes narrow. As a result, the processing time of the mold 10A can be reduced. Moreover, wear of the processing tool can be reduced, and the manufacturing cost of the mold 10A can be reduced.
[Second Embodiment]
(Substrate 1A)
A method for manufacturing an optical element according to the second embodiment of the present invention will be described. In the second embodiment, two rod-shaped cut pieces are produced from one base material. With reference to FIG. 9, the base material which concerns on 2nd Embodiment is demonstrated. FIG. 9 is a perspective view of the base material. The same components as those according to the first embodiment may be denoted by the same reference numerals and description thereof may be omitted.

The substrate 1A is a rod-shaped prism having a triangular cross-sectional shape. The substrate 1A is a prism (triangular prism) having an isosceles triangular bottom surface 2 and bottom surface 3 having a base angle of (90 ° −θ). The side surface of the substrate 1 includes a surface 4, a surface 5, and a surface 6. The angle formed between the surface 4 and the surface 6 is an angle (90 ° −θ) (0 ° <θ <90 °, for example, θ = 45 °), and the angle formed between the surface 5 and the surface 6 is an angle (90 ° -θ). The surface 4 includes one side of two equal sides in the isosceles triangle (the bottom surface 2 and the bottom surface 3). The surface 5 includes the other of the two equal sides in the isosceles triangle (the bottom surface 2 and the bottom surface 3). The surface 6 includes the bases of isosceles triangles (the bottom surface 2 and the bottom surface 3). The length of each side of the bottom surface 2 and the bottom surface 3 is preferably about 3 mm to 5 mm. The material of the base 1A is, for example, glass. Similar to the first embodiment, it is preferable that the surface 6 is preliminarily surface-finished with high surface accuracy.
(Mold 10B for transferring diffraction grating)
With reference to FIG. 10, the metal mold | die which concerns on 2nd Embodiment is demonstrated. FIG. 10 is a front view of the mold. On one surface 11 of the mold 10B, a transfer structure 12A and a transfer structure 12B are formed at a predetermined distance. The transfer structure 12A and the transfer structure 12B are structures for transferring a blazed diffraction grating. Each of the transfer structure 12A and the transfer structure 12B has a plurality of grooves along one direction. The cross-sectional shape of the groove is serrated. The shapes of the transfer structure 12A and the transfer structure 12B are inverted from each other (inverted shape). Specifically, the saw blades face in opposite directions in the transfer structure 12A and the transfer structure 12B. Further, the plurality of grooves in the transfer structure 12A and the plurality of grooves in the transfer structure 12B are parallel, and the transfer structure 12A and the transfer structure 12B are formed in parallel. For example, when the midpoint between the transfer structure 12A and the transfer structure 12B (for example, the center of the mold 10B) is used as a reference, the structure composed of the transfer structure 12A and the transfer structure 12B is point-symmetric.

In FIG. 10, the pitch of the transfer structure 12 A and the transfer structure 12 B is illustrated in an enlarged manner for explanation, but the actual pitch is a fine pitch on the order of submicrons.
(Optical element manufacturing method)
A method for manufacturing an optical element according to the second embodiment will be described with reference to FIGS.
(1. Formation of diffraction grating)
First, similarly to the manufacturing method according to the first embodiment, a diffraction grating is formed on the surface 6 of the substrate 1A by the nanoimprint method. Specifically, a photocurable resin is applied to the surface 11 of the mold 10B, and the resin is provided on the transfer structure 12A and the transfer structure 12B. The surface 6 (transfer surface) of the substrate 1A is pressed against the transfer structure 12A and the transfer structure 12B coated with resin, and the resin is cured by irradiating ultraviolet rays. Thereby, a diffraction grating is formed on the surface 6 of the substrate 1A. Here, (1. Formation of diffraction grating) functions as the first step in the present invention, surface 6 functions as the surface and first side surface in the present invention, and surface 5 and surface 4 correspond to the present invention. Functions as the second and third side surfaces.
(Base material 1A on which a diffraction grating is formed)
FIG. 11 shows a substrate 1A on which a diffraction grating is formed. FIG. 11 is a front view of the substrate. A fine pitch diffraction grating 7A and a diffraction grating 7B are formed on the surface 6 of the substrate 1A. The diffraction grating 7A is a diffraction grating formed by the transfer structure 12A. The diffraction grating 7B is a diffraction grating formed by the transfer structure 12B. The diffraction grating 7A and the diffraction grating 7B are inverted in shape. That is, the diffraction grating 7A and the diffraction grating 7B are in an inverted shape. Specifically, the blazed shapes of the diffraction grating 7A and the diffraction grating 7B are directed in opposite directions. The diffraction grating 7 A is formed from the center of the surface 6 to the surface 5. The diffraction grating 7 B is formed from the center of the surface 6 to the surface 4. For example, when the center of the surface 6 is used as a reference, the structure composed of the diffraction grating 7A and the diffraction grating 7B is point-symmetric. Here, the diffraction grating 7A and the diffraction grating 7B function as the first microstructure and the second microstructure in the present invention.

In FIG. 11, the pitches of the diffraction grating 7A and the diffraction grating 7B are shown enlarged for the sake of explanation, but the actual pitch is a fine pitch on the order of submicrons.

A reflective film such as gold (Au) is formed on the surface 6 on which the diffraction grating 7A and the diffraction grating 7b are formed.
(2. Cutting process)
Next, a plurality of optical elements are manufactured by cutting the base material 1A on which the diffraction grating 7A and the diffraction grating 7B are formed. The cutting process will be described with reference to FIGS. 12 and 13 are front views showing a state in which the base material is placed on the processing table.
(2-A. Fixed)
As shown in FIG. 12, the base 1 A is fixed to the processing table 20 with the cutting reference plane of the base 1 A facing the upper surface 21 of the processing table 20. In the second embodiment, the cutting reference plane of the substrate 1A is the plane 5 at first, and then replaced with the plane 4.

For example, the base 5 A is fixed to the processing table 20 with the surface 5 of the base 1 A as the cutting reference surface and the surface 5 facing the upper surface 21 of the processing table 20. For example, the dicing sheet 22 is provided on the upper surface 21 of the processing table 20, and the base material 1 A is provided on the dicing sheet 22 by bringing the dicing sheet 22 and the surface 5 into contact with each other. Alternatively, the base 1 A may be provided on the processing table 20 by a fixing means such as a clamp without providing the dicing sheet 22.
(2-B. Cutting)
After fixing the substrate 1A to the processing table 20, the substrate 1A is cut at a position where the diffraction grating 7A is formed. Specifically, the substrate 1A is cut along a cut surface D (first cut surface) intersecting with the diffraction grating 7A (first cutting step). The cutting plane D is a plane that is parallel to the longitudinal direction (X direction) of the substrate 1A and perpendicular to the cutting reference plane (plane 5). In other words, the cutting plane D is a plane that is parallel to the ridgeline formed by the

planes

4 and 5 and is perpendicular to the cutting reference plane (plane 5). Next, the substrate 1A is cut along a cut surface E (second cut surface) that is parallel to the cut surface D and spaced a predetermined distance inside the cut surface D (second cutting step). The cut surface E intersects the diffraction grating 7A. Note that the cut surface D and the cut surface E may not be perpendicular to the cutting reference surface (surface 5). Moreover, the cut surface D and the cut surface E do not need to be parallel. The second cutting step may be performed first, and then the first cutting step may be performed.

By cutting the substrate 1A along the cut surface D and the cut surface E as described above, the rod-shaped first cut piece 40 is obtained. The rod-shaped first cut piece 40 has the same shape as the cut piece 30 shown in FIG.

Similar to the method shown in FIG. 6, a plurality of optical elements are obtained by cutting the first cut pieces 40 at a plurality of locations at predetermined intervals along the cut surface C (third cut surface). Cutting step). Thereby, the optical element 30A shown in FIG. 7 is obtained.
(2-C. Fixed)
Next, as shown in FIG. For example, the base material 1A is rotated to the right by a rotation axis perpendicular to the paper surface so that the surface 4 faces the upper surface 21 of the processing table 20. For example, the base material 1 A is fixed to the processing table 20 by bringing the dicing sheet 22 and the surface 4 into contact with each other.
(2-D. Cutting)
After fixing the substrate 1A to the processing table 20, the substrate 1A is cut at a position where the diffraction grating 7B is formed. Specifically, the substrate 1A is cut along a cut surface F (fourth cut surface) intersecting with the diffraction grating 7B (fourth cutting step). The cutting surface F is a surface that is parallel to the longitudinal direction (X direction) of the substrate 1A and is perpendicular to the cutting reference surface (surface 4). In other words, the cutting plane F is a plane that is parallel to the ridgeline formed by the plane 4 and the plane 5 and is perpendicular to the cutting reference plane (plane 4). Next, the substrate 1A is cut along a cut surface G (fifth cut surface) parallel to the cut surface F and spaced a predetermined distance inside the cut surface F (fifth cutting step). The cut surface G intersects the diffraction grating 7B. Note that the cut surface F and the cut surface G may not be perpendicular to the cutting reference surface (surface 4). Moreover, the cut surface F and the cut surface G do not need to be parallel.

By cutting the substrate 1A along the cut surface F and the cut surface G as described above, a rod-shaped second cut piece 41 is obtained. The rod-shaped second cut piece 41 has the same shape as the cut piece 30 shown in FIG.

Similar to the method shown in FIG. 6, a plurality of optical elements are obtained by cutting the second cut pieces 41 at a plurality of locations at predetermined intervals along the cut surface C (sixth cut surface) (sixth cut surface). Cutting step). Thereby, the optical element 30A shown in FIG. 7 is obtained.

As described above, according to the manufacturing method according to the second embodiment, the same effects as the manufacturing method according to the first embodiment can be obtained. Furthermore, since two cut pieces (the first cut piece 40 and the second cut piece 41) can be obtained from one base material 1A, the material cost can be suppressed. As a result, the manufacturing cost of the optical element can be reduced.
(Modification 2)
Also in the second embodiment, like the first modification of the first embodiment, the diffraction grating 7 may be formed only in a range including the effective optical surface of the surface 35 of the optical element 30A. In FIG. 14, the metal mold | die of the modification 2 is shown. FIG. 14 is a front view of the mold. On one surface 11 of the mold 10C, a transfer structure 12A and a transfer structure 12B are formed in a partial region at a predetermined distance. The shapes of the transfer structure 12A and the transfer structure 12B are inverted from each other (inverted shape). Each of the transfer structure 12A and the transfer structure 12B is wider than the effective optical surface of the surface 35 of the optical element 30A. Further, the combined range of the transfer structure 12A and the transfer structure 12B is narrower than the surface 6 of the substrate 1A. Using this mold 10C, the diffraction grating 7A and the diffraction grating 7B are formed on the surface 6 of the substrate 1A. Thereby, the diffraction grating 7A and the diffraction grating 7B are formed in a partial region of the surface 6 of the substrate 1A. By cutting the substrate 1A, the first cut piece 40 and the second cut piece 41 are obtained. By cutting the first cut piece 40 and the second cut piece 41, a plurality of optical elements 30A are obtained. According to the second modification, the same effect as the first modification described above can be obtained.
[Third Embodiment]
(Substrate 1B)
An optical element manufacturing method according to the third embodiment of the present invention will be described. The optical element according to the first embodiment and the second embodiment can be used as a surface reflection type microprism with a diffraction grating. In the third embodiment, an optical element that can be used as a microprism with an internal reflection type diffraction grating is manufactured. With reference to FIG. 15, the base material which concerns on 3rd Embodiment is demonstrated. FIG. 15 is a perspective view of the substrate. The same components as those according to the first embodiment may be denoted by the same reference numerals and description thereof may be omitted.

The base material 1B is a rod-shaped prism having a triangular cross section. Specifically, the base material 1 B is a prism (triangular prism) having a triangular bottom surface 2 and a bottom surface 3. For example, the surface 4 and the surface 5 are orthogonal to each other, and the surface 6 is inclined with respect to the surface 4 and the surface 5. For example, the angle formed by the surface 5 and the surface 6 is an angle (90 ° −θ) (0 ° <θ <90 °). The length of each side of the bottom surface 2 and the bottom surface 3 is preferably about 3 mm to 5 mm. The material of the substrate 1B is, for example, glass. For example, the surface 5 and the surface 6 are polished into a mirror surface in advance by polishing the surface 5 and the surface 6. Further, it is preferable to form an antireflection film on the surface 5 in advance. In the optical element obtained from the substrate 1B, the surface 5 corresponds to the incident surface. In the third embodiment, a diffraction grating is formed on the surface 6.
(Mold 10D for transferring diffraction grating)
With reference to FIG. 16, the metal mold | die which concerns on 3rd Embodiment is demonstrated. FIG. 16 is a front view of the mold. A transfer structure 12 is formed in a partial area on one surface 11 of the mold 10D. The range in which the transfer structure 12 is formed is narrower than the surface 6 of the substrate 1B and wider than the effective optical surface of the diffraction grating surface of the optical element (microprism) obtained from the substrate 1B. The diffraction grating surface is a surface on which a diffraction grating is formed. Thereby, a diffraction grating is formed in a partial region of the surface 6 of the substrate 1B. In FIG. 16, for the sake of explanation, the pitch of the transfer structure 12 is shown enlarged, but the actual pitch is a fine pitch on the order of submicrons.
(Optical element manufacturing method)
With reference to FIGS. 17 to 19, a method of manufacturing an optical element according to the second embodiment will be described.
(1. Formation of diffraction grating)
First, similarly to the manufacturing method according to the first embodiment, a diffraction grating is formed on the surface 6 of the substrate 1B by the nanoimprint method. Specifically, a photocurable resin is applied to the surface 11 of the mold 10 D, and the resin is provided on the transfer structure 12. The surface 6 (transfer surface) of the substrate 1B is pressed against the transfer structure 12 coated with the resin, and the resin is cured by irradiating with ultraviolet rays. Thereby, a diffraction grating is formed in a partial region of the surface 6 of the substrate 1B. Here, (1. Formation of diffraction grating) functions as the first step in the present invention, the surface 6 functions as the surface and the first side surface in the present invention, and the surface 5 corresponds to the second step in the present invention. Acts as a side of
(Base material 1B on which a diffraction grating is formed)
FIG. 17 shows a substrate 1B on which a diffraction grating is formed. FIG. 17 is a front view showing a state where the base material is placed on the processing table. A fine pitch diffraction grating 7 is formed on a part of the surface 6 of the substrate 1B. In FIG. 17, the pitch of the diffraction grating 7 is illustrated in an enlarged manner for explanation, but the actual pitch is a fine pitch on the order of submicrons. A reflective film such as gold (Au) is formed on the surface 6 on which the diffraction grating 7 is formed.
(2. Cutting process)
Next, a plurality of optical elements are manufactured by cutting the base material 1B on which the diffraction grating 7 is formed. The cutting process will be described with reference to FIG.
(2-A. Fixed)
As shown in FIG. 17, the base 1 B is fixed to the processing table 20 with the cutting reference surface of the base 1 B facing the upper surface 21 of the processing table 20. For example, the substrate 5 is fixed to the processing table 20 with the surface 5 of the substrate 1 B as the cutting reference surface and the surface 5 facing the upper surface 21 of the processing table 20. For example, the dicing sheet 22 is provided on the upper surface 21 of the processing table 20, the dicing sheet 22 is brought into contact with the surface 5, and the base material 1 B is provided on the dicing sheet 22. Or you may provide the base material 1B in the process stand 20 by fixing means, such as a clamp, without providing the dicing sheet 22.
(2-B. Cutting)
After fixing the base material 1B to the processing table 20, the base material 1B is cut at a position where the diffraction grating 7 is formed. Specifically, the substrate 1B is cut along the cutting plane H that intersects the diffraction grating 7 (first cutting step). The cutting surface H is a surface that is parallel to the longitudinal direction (X direction) of the base material 1B and is perpendicular to the cutting reference surface (surface 5). In other words, the cutting plane H is a plane that is parallel to the ridgeline formed by the

planes

4 and 5 and is perpendicular to the cutting reference plane (plane 5). Next, the base material 1B is cut along a cut surface I that is parallel to the cut surface H and spaced a predetermined distance inward from the cut surface H (second cutting step). The cut surface I intersects the diffraction grating 7. Note that the cutting plane H and the cutting plane I do not have to be perpendicular to the cutting reference plane (plane 5). Moreover, the cut surface H and the cut surface I do not need to be parallel.

By cutting the substrate 1B along the cut surface H and the cut surface I as described above, a rod-shaped cut piece 50 is obtained. The rod-shaped cut piece 50 has substantially the same shape as the cut piece 30 shown in FIG. FIG. 18 shows a cut piece 50. FIG. 18 is a front view of the cut piece. The cut piece 50 is a prism having a substantially trapezoidal surface 51 and a substantially trapezoidal surface (not shown) facing the surface 51 as a bottom surface. The surface 51 corresponds to the bottom surface 2 of the substrate 1. The surface facing the surface 51 corresponds to the bottom surface 3 of the substrate 1. The side surface of the cut piece 50 includes a surface 53, a surface 54, a surface 55, and a surface 56. The surface 53 corresponds to the cut surface H and includes the upper base of the trapezoid (surface 51). The surface 54 corresponds to the cut surface I and includes the lower base of the trapezoid (surface 51). The surface 55 corresponds to the surface 6 of the substrate 1 and is inclined with respect to the surface 53 and the surface 54. The angle formed by the surface 54 and the surface 55 is an angle θ (0 ° <θ <90 °, for example, θ = 45 °). A diffraction grating 7 is formed on the surface 55 (surface 6). The surface 56 corresponds to the surface 5 of the substrate 1 and is orthogonal to the surface 53 and the surface 54.

The surface 53 and the surface 54 may be parallel or may not be parallel. That is, by cutting the substrate 1B with the cut surface H and the cut surface I parallel, a cut piece 50 in which the surface 53 and the surface 54 are parallel is obtained. By cutting the substrate 1B with the cut surface H and the cut surface I being non-parallel, a cut piece 50 in which the surface 53 and the surface 54 are non-parallel is obtained.

Then, the tip (ridge line formed by the surface 54 and the surface 55) having an angle θ is chamfered (cut) to the cut surface J. FIG. 19 shows the cut piece 50 after chamfering. FIG. 19 is a front view of the cut piece 50 after chamfering. The surface 57 of the cutting piece 50 is a surface formed by chamfering and corresponds to the cutting surface J.

As in the first embodiment, a plurality of optical elements are manufactured by cutting the chamfered cut pieces 50 at a plurality of locations at predetermined intervals along the cut surface C (third cutting step).

The optical element according to the third embodiment can be used as an internal reflection type microprism with a diffraction grating. For example, light enters the surface 56 from the outside of the optical element, travels inside the optical element, and reaches the surface 55. The light is reflected and diffracted by the surface 55, travels to the surface 56, and exits from the surface 56 to the outside of the optical element.

As described above, the same effect as that of the manufacturing method according to the first embodiment can be obtained also in the case of producing the internal reflection type microprism with a diffraction grating.

For example, when the optical element according to the third embodiment is used for an optically assisted magnetic head, it is preferable that the angle formed by the surface 54 and the surface 56 of the optical element is smaller than 90 °. That is, it is preferable to cut the base material 1B by inclining the cutting plane I with respect to the cutting reference plane (plane 5). For example, the surface 53 and the surface 54 are formed non-parallel so that the angle formed by the surface 54 and the surface 56 is less than 90 °. While the magnetic head floats with respect to the disk during operation, the magnetic head is tilted by the wind pressure of the disk rotation. In the magnetic head, the surface 56 of the microprism (the optical element according to the third embodiment) is fixed to the tip of the slider, and the surface 54 faces the disk. By making the angle between the surface 54 and the surface 56 of the optical element (microprism) smaller than 90 °, even if the magnetic head is tilted, collision between the optical element (microprism) and the disk can be avoided. A highly reliable hard disk device can be obtained.
[Fourth Embodiment]
(Substrate 1C)
A method for manufacturing an optical element according to the fourth embodiment of the present invention will be described. In the fourth embodiment, the manufacturing method according to the second embodiment is applied to produce the internal reflection type diffraction prism with a diffraction grating according to the third embodiment. With reference to FIG. 20, the base material which concerns on 4th Embodiment is demonstrated. FIG. 20 is a perspective view of the base material. The same components as those according to the first embodiment may be denoted by the same reference numerals and description thereof may be omitted.

The base material 1C is a rod-shaped prism having a triangular cross-sectional shape. The substrate 1C is a prism (triangular prism) having an isosceles triangular bottom surface 2 and bottom surface 3 having a base angle of (90 ° −θ). Specifically, the angle formed by the surface 4 and the surface 6 is (90 ° −θ) (0 ° <θ <90 °), and the angle formed by the surface 5 and the surface 6 is (90 ° −θ ). The side surface of the substrate 1 includes a surface 4, a surface 5, and a surface 6. The surface 4 includes one side of two equal sides in the isosceles triangle (the bottom surface 2 and the bottom surface 3). The surface 5 includes the other of the two equal sides in the isosceles triangle (the bottom surface 2 and the bottom surface 3). The surface 6 includes the bases of isosceles triangles (the bottom surface 2 and the bottom surface 3). The length of each side of the bottom surface 2 and the bottom surface 3 is preferably about 3 mm to 5 mm. The material of the substrate 1C is, for example, glass. For example, the surface 4, the surface 5 and the surface 6 are polished, so that the surface 4, the surface 5 and the surface 6 are processed into mirror surfaces in advance. Further, it is preferable to form an antireflection film on the surface 4 and the surface 5 in advance. In the optical element obtained from the substrate 1C, the surface 4 and the surface 5 correspond to the incident surface. In the fourth embodiment, a diffraction grating is formed on the surface 6.
(Mold 10E for forming a diffraction grating)
With reference to FIG. 21, the metal mold | die which concerns on 4th Embodiment is demonstrated. FIG. 21 is a front view of the mold. On one surface 11 of the mold 10E, a transfer structure 12A and a transfer structure 12B are formed at a predetermined distance. The transfer structure 12A and the transfer structure 12B are structures for transferring a blazed diffraction grating. The shapes of the transfer structure 12A and the transfer structure 12 are reversed (reverse shape). Similarly to the second modification of the second embodiment shown in FIG. 14, the transfer structure 12A and the transfer structure 12B are each formed in a partial region. For example, the transfer structure 12A and the transfer structure 12B are each narrower than the surface 6 of the substrate 1C and wider than the effective optical surface of the diffraction grating surface of the optical element (microprism) obtained from the substrate 1C. Using this mold 10E, a diffraction grating is formed on the surface 6 of the substrate 1C. In FIG. 21, the pitch of the transfer structure 12A and the transfer structure 12B is depicted enlarged for the sake of explanation, but the actual pitch is a fine pitch on the order of submicrons.
(Optical element manufacturing method)
With reference to FIGS. 22-24, the manufacturing method of the optical element which concerns on 4th Embodiment is demonstrated.
(1. Formation of diffraction grating)
First, similarly to the manufacturing method according to the first embodiment, a diffraction grating is formed on the surface 6 of the substrate 1C by the nanoimprint method. Specifically, a photocurable resin is applied to the surface 11 of the mold 10E, and the resin is provided on the transfer structure 12A and the transfer structure 12B. The surface (transfer surface) of the substrate 1C is pressed against the transfer structure 12A and the transfer structure 12B coated with resin, and the resin is cured by irradiating ultraviolet rays. Thereby, a diffraction grating is formed on the surface 6 of the substrate 1C. Here, (1. Formation of diffraction grating) functions as the first step in the present invention, surface 6 functions as the surface and first side surface in the present invention, and surface 5 and surface 4 correspond to the present invention. Functions as the second and third side surfaces.
(Base material 1C on which diffraction grating is formed)
FIG. 22 shows a substrate 1C on which a diffraction grating is formed. FIG. 22 is a front view of the substrate. A fine pitch diffraction grating 7A and a diffraction grating 7B are formed in a partial region of the surface 6 of the substrate 1C. The diffraction grating 7A is a diffraction grating formed by the transfer structure 12A. The diffraction grating 7B is a diffraction grating formed by the transfer structure 12B. The diffraction grating 7A and the diffraction grating 7B are inverted in shape (inverted shape). In FIG. 22, for the sake of explanation, the pitch of the diffraction grating 7A and the diffraction grating 7B is depicted enlarged, but the actual pitch is a fine pitch on the order of submicrons. A reflective film such as gold (Au) is formed on the surface 6 on which the diffraction grating 7A and the diffraction grating 7B are formed.
(2. Cutting process)
Next, a plurality of optical elements are manufactured by cutting the substrate 1C on which the diffraction grating 7A and the diffraction grating 7B are formed. The cutting process will be described with reference to FIGS. FIG.23 and FIG.24 is a front view which shows the state which mounted the base material on the process stand.
(2-A. Fixed)
As shown in FIG. 23, the base material 1 C is fixed to the work table 20 with the cutting reference surface of the base material 1 C facing the upper surface 21 of the work table 20. In the fourth embodiment, the cutting reference plane of the substrate 1 C is the plane 5 at first, and then replaced with the plane 4.

For example, the substrate 5 is fixed to the processing table 20 with the surface 5 of the substrate 1 C as a reference cut surface and the surface 5 facing the upper surface 21 of the processing table 20. For example, the dicing sheet 22 is provided on the upper surface 21 of the processing table 20, and the substrate 1 C is provided on the dicing sheet 22 by bringing the dicing sheet 22 and the surface 5 into contact with each other. Alternatively, the substrate 1C may be provided on the processing table 20 by a fixing means such as a clamp without providing the dicing sheet 22.
(2-B. Cutting)
After fixing the base material 1C to the processing table 20, the base material 1C is cut at a position where the diffraction grating 7A is formed. Specifically, the substrate 1C is cut along the cut surface K intersecting the diffraction grating 7A (first cutting step). The cutting plane K is a plane that is parallel to the longitudinal direction (X direction) of the substrate 1C and perpendicular to the cutting reference plane (plane 5). In other words, the cutting plane K is a plane that is parallel to the ridgeline formed by the plane 4 and the plane 5 and is perpendicular to the cutting reference plane (plane 5). Next, the substrate 1 C is cut along a cutting surface L that is parallel to the cutting surface K and is a predetermined distance inside the cutting surface K (second cutting step). The cut surface L intersects the diffraction grating 7A. Note that the cut surface K and the cut surface L may not be perpendicular to the cutting reference surface (surface 5). Moreover, the cut surface K and the cut surface L do not need to be parallel.

By cutting the substrate 1C along the cut surface K and the cut surface L as described above, the rod-shaped first cut piece 60 is obtained. The rod-shaped first cut piece 60 has substantially the same shape as the cut piece 50 shown in FIG.
(2-C. Fixed)
Next, as shown in FIG. For example, the base material 1 C is rotated to the right by a rotation axis perpendicular to the paper surface so that the surface 4 faces the upper surface 21 of the processing table 20. For example, the base material 1 C is fixed to the processing table 20 by bringing the dicing sheet 22 and the surface 4 into contact with each other.
(2-D. Cutting)
After fixing the base material 1C to the processing table 20, the base material 1C is cut at a position where the diffraction grating 7B is formed. Specifically, the substrate 1C is cut along the cut surface M intersecting the diffraction grating 7B (fourth cutting step). The cutting plane M is a plane that is parallel to the longitudinal direction (X direction) of the substrate 1C and perpendicular to the cutting reference plane (plane 4). In other words, the cutting plane M is a plane that is parallel to the ridgeline formed by the

planes

4 and 5 and is perpendicular to the cutting reference plane (plane 4). Next, the substrate 1 C is cut along a cut surface N that is parallel to the cut surface M and is a predetermined distance inside the cut surface M (fifth cutting step). The cut surface N intersects the diffraction grating 7B. Note that the cutting surface M and the cutting surface N do not have to be perpendicular to the cutting reference surface (surface 4). Moreover, the cut surface M and the cut surface N do not need to be parallel.

By cutting the substrate 1C along the cut surface M and the cut surface N as described above, a rod-shaped second cut piece 61 is obtained. The rod-shaped second cut piece 61 has the same shape as the cut piece 50 shown in FIG.

And in the 1st cutting piece 60 and the 2nd cutting piece 61, the front-end | tip part which has angle (theta) is chamfered. The first cut piece 60 and the second cut piece 61 after chamfering have the same shape as the cut piece 50 after chamfering shown in FIG. Then, similarly to the first embodiment, a plurality of optical elements are obtained by cutting the first cut piece 60 and the second cut piece 61 after chamfering at a plurality of locations at predetermined intervals along the cut surface C. (Third and sixth cutting steps). Thereby, similarly to the optical element according to the third embodiment, an internal reflection type microprism with a diffraction grating is obtained.

As mentioned above, according to the manufacturing method which concerns on 4th Embodiment, there can exist the same effect as the manufacturing method which concerns on 1st Embodiment. Furthermore, since two cut pieces (the first cut piece 60 and the second cut piece 61) can be obtained from one base material 1C, the material cost can be suppressed. As a result, the manufacturing cost of the optical element can be reduced.

In the first to fourth embodiments described above, the fine structure formed on the substrate 1 is not limited to the diffraction grating, and may be another structure. For example, the shape formed on the substrate 1 by the nanoimprint method is not limited to the shape of the diffraction grating, and may be a spherical or aspherical lens shape or a hologram lens shape.

1, 1A, 1B,

1C Base material

2, 3

Bottom surface

4, 5, 6, 11, 31, 32, 33, 34, 35, 36, 37, 38, 51, 53, 54, 55, 56, 57 Surface 7 7A, 7B Diffraction grating 10, 10A, 10B, 10C, 10D,

10E Die

12, 12A, 12B Transfer structure 13 Resin 14 Ultraviolet 20 Processing table 21 Upper surface 22 Dicing sheet (dicing tape)
23

Dicing blade

30, 40, 41, 50, 60, 61 Cut piece 30A Optical element A, B, C, D, E, F, G, H, I, J, K, L, M, N Cut surface

Claims

A first step of forming a microstructure on the surface of the rod-shaped substrate;
A first cutting step of cutting the substrate at a first cut surface that intersects the surface and extends along the longitudinal direction of the substrate;
The first cut surface and the second cut surface are cut at a predetermined distance from the first cut surface by cutting the substrate with a second cut surface that intersects the surface and extends along the longitudinal direction. A second cutting step of obtaining a cut piece sandwiched between and from the base material,
A third cutting step of producing a plurality of optical elements by cutting the cut pieces at a predetermined interval at a third cut surface intersecting the first cut surface and the second cut surface;
The manufacturing method of the optical element characterized by the above-mentioned.
The base material is a triangular prism having a triangular bottom surface,
In the first step, the microstructure is formed with the first side surface of the triangular prism as the surface,
In the first cutting step, the base material is cut at the first cut surface that intersects the second side surface of the triangular prism and the first side surface and extends along the longitudinal direction,
In the second cutting step, at the predetermined distance from the first cut surface, the second side surface and the first side surface intersect with the second side surface and the second cut surface along the longitudinal direction. The method for producing an optical element according to claim 1, wherein the substrate is cut.
An angle formed by the first side surface and the second side surface is 90 ° −θ (0 ° <θ <90 °),
In the first cutting step, the substrate is cut at the first cutting surface perpendicular to the second side surface;
3. The method of manufacturing an optical element according to claim 2, wherein, in the second cutting step, the base material is cut at the second cutting surface perpendicular to the second side surface.
The base material is a triangular prism having an isosceles triangular base,
In the first step, the microstructure is formed with the first side surface including the bottom of the triangular prism as the surface,
In the first cutting step, the first cut surface along the longitudinal direction intersects the second side surface and the first side surface including one side of two equal sides of the isosceles triangle, Cutting the substrate;
In the second cutting step, at the predetermined distance from the first cut surface, the second side surface and the first side surface intersect with the second side surface and the second cut surface along the longitudinal direction. By cutting the substrate, a first cut piece sandwiched between the first cut surface and the second cut surface is obtained from the substrate,
In the third cutting step, the plurality of optical elements are manufactured by cutting the first cut piece at the predetermined interval at the third cut surface,
A fourth cut surface that cuts the base material at a fourth cut surface that intersects the first side surface and intersects with a third side surface that includes the other two sides of the two isosceles triangles that are equal. Cutting process;
Cutting the substrate at a predetermined distance from the fourth cut surface by cutting the base material at a fifth cut surface that intersects the third side surface and the first side surface and extends along the longitudinal direction, respectively. A fifth cutting step of obtaining a second cut piece sandwiched between a fourth cut surface and the fifth cut surface from the substrate;
A sixth cut surface intersecting the fourth cut surface and the fifth cut surface cuts the second cut piece at the predetermined interval, thereby producing the plurality of optical elements. Cutting process;
The method of manufacturing an optical element according to claim 1, further comprising:
The base angle of the isosceles triangle is 90 ° −θ (0 ° <θ <90 °),
In the first cutting step, the substrate is cut at the first cutting surface perpendicular to the second side surface;
In the second cutting step, the substrate is cut at the second cut surface perpendicular to the second side surface,
In the fourth cutting step, the substrate is cut at the fourth cut surface perpendicular to the third side surface,
5. The method of manufacturing an optical element according to claim 4, wherein, in the fifth cutting step, the base material is cut at the fifth cutting surface perpendicular to the third side surface.
In the first step, the fine structure including a first fine structure and a second fine structure having mutually inverted shapes is formed on the first side surface,
In the first cutting step and the second cutting step, the first cut surface and the second cut surface that intersect the second side surface and the first microstructure, respectively, Obtaining the first cut piece by cutting the substrate,
In the fourth cutting step and the fifth cutting step, the fourth cut surface and the fifth cut surface intersecting the third side surface and the second microstructure, respectively, 6. The method of manufacturing an optical element according to claim 4, wherein the second cut piece is obtained by cutting a base material.
7. The optical film is formed on the surface on which the fine structure is formed between the first step and the first cutting step. 8. A method for manufacturing an optical element.
The method of manufacturing an optical element according to claim 7, wherein the optical film is a reflective film.
The optical element according to any one of claims 1 to 8, wherein a tip portion including the surface on which the fine structure is formed and a surface formed by the second cut surface is chamfered. Production method.
The method for manufacturing an optical element according to any one of claims 1 to 9, wherein the first cut surface and the second cut surface are not parallel to each other.
In the first step, a flowable material is provided between the mold having the microstructure and the base material, and the flowable material is sandwiched between the mold and the base material, The fine structure is transferred to the flowable material, and the fine structure is formed on the surface of the substrate by curing the flowable material to which the fine structure is transferred. The manufacturing method of the optical element in any one of Claims 1-10.
12. The method of manufacturing an optical element according to claim 11, wherein the fluid material is a resin.
In the first step, the microstructure is formed in a partial region of the surface;
In the first cutting step and the second cutting step, the substrate is cut at the first cut surface and the second cut surface that intersect the position where the microstructure is formed. The method for manufacturing an optical element according to any one of claims 1 to 12, wherein
14. The method of manufacturing an optical element according to claim 13, wherein in the first step, the fine structure is formed in a region wider than an effective optical surface of the optical element in a partial region of the surface. .
15. The method of manufacturing an optical element according to claim 1, wherein the fine structure is a diffraction grating.